Cleanup: Initialize closure weight to silence warning on Windows

This appears to be a false positive. It warns when the
function gets called with this argument, but the function
does not actually use it.

Pull Request: https://projects.blender.org/blender/blender/pulls/146175

intern/cycles/kernel/svm/svm.h

@@ -102,7 +102,8 @@ ccl_device void svm_eval_nodes(KernelGlobals kg,
                                const uint32_t path_flag)
 {
   float stack[SVM_STACK_SIZE];
-  Spectrum closure_weight;
+  /* Initialiez to silence (false positive?) warning about uninitialzied use on Windows. */
+  Spectrum closure_weight = zero_spectrum();
   int offset = sd->shader & SHADER_MASK;
 
   while (true) {